An ignition coil device in which an insulating resin material is vacuum-filled into the whole of a housing is disclosed as a stick-type ignition coil device in U.S. Pat. No. 6,417,752 (JP-2001-185430A). An axial cross-sectional view of an ignition coil device of the same type as the ignition coil device disclosed in the above patent document is shown in FIG. 13. As shown in this figure, an ignition coil device 100 has a center core 101, a secondary spool 102, a secondary coil 103, a primary spool 104, a primary coil 105, an outer peripheral core 106, a housing 107, and a high voltage tower 108.
The housing 107 is shaped like a cylinder. The center core 101 is shaped like a round bar and is arranged nearly in the radial center of the housing 107. The secondary spool 102 is cylindrical and is arranged on the outer peripheral side of the center core 101. The secondary coil 103 is wound around the outer peripheral surface of the secondary spool 102. The primary spool 104 is cylindrical and is arranged on the outer peripheral side of the secondary coil 103. The primary coil 105 is wound around the outer peripheral surface of the primary spool 104. The outer peripheral core 106 is shaped like a cylinder with a slit and is arranged on the outer peripheral side of the primary coil 105. The high voltage tower 108 covers the bottom end opening of the housing 107.
An insulating resin material 109 is epoxy resin and is filled from the top end opening of the housing 107 into the housing 107 and the high voltage tower 108 which are evacuated to a vacuum. The insulating resin material 109 is cured in the spaces between the respective parts.
The above ignition coil device 100 is manufactured in the following manner. First, the center core 101, the secondary spool 102, the secondary coil 103, the primary spool 104, the primary coil 105 and the outer peripheral core 106 are mounted in the housing 107 and The bottom end opening of the housing 107 is closed by the high voltage tower 108. A case having a top end opening is formed by the housing 107 and the high voltage tower 108. Next, the insulating resin material 109 is vacuum-filled at a time from the top opening of the housing 107. The insulating resin material 109 is filled into the spaces between the respective parts described above. The insulating resin material 109 is cured in the spaces between the respective parts.
Here, the insulating resin material 109 is filled so as to fix the respective parts constructing the ignition coil device 100. The insulating resin material 109 is filled so as to secure the insulation between the respective parts.
However, the ignition coil device 100 has portions which need to be insulated and fixed and has portions which do not need to be insulated but is good enough to be fixed. Moreover, the ignition coil device 100 has portions which do not need to be insulated and fixed, that is, which do not need be filled itself of the insulating resin material 109.
However, according to the above method of manufacturing the ignition coil device 100, the insulating resin material 109 is filled into the whole of the ignition coil device 100. Namely, although the needs of the respective parts of the ignition coil device 100 for the insulating resin material 109 are different from each other, the same insulating resin material 109 is distributed to all of the parts. For this reason, there is no other choice but to use a resin material having an excellent insulating property and a fixing property as the insulating resin material 109. Hence, this results in increasing the cost of the insulating resin material 109 and the manufacturing cost of the ignition coil device 100 itself.